Retrode is accepting preorders for a USB adaptor to allow vintage 16-bit Sega Genesis/Mega Drive and Nintendo SNES/SFC games on a PC. The hardware includes ports for controllers from each system, and optimistically promises "Driverless operation on any USB host, under any OS, using any emulator." MCV notes that the legality of such a device is not entirely clear, though the fact that this still requires an emulator may work in its favor (I am not a lawyer).

Looks like its $85. A bit steep, but if someone has a decent collection of played carts (not a collection of boxes in shrink to just look at) and controllers they want to use, then I'm sure it will be worth it.

In the past, I've purchased a USB to SNES controller adapter so I could play SNES games on an emulator with the original controller from my SNES. Things like that use the HID driver built into windows so they don't need a installable driver. So the controller part would easily work like that. The question is, how would the other part? The easiest way I can think of off hand would be to have some sorta video output to plug into a monitor.

Alternatively, maybe they will make it like a disk drive so emulator can read the cart directly (although I don't know how many emulators can even do this, so that would kinda make the promise of "any OS any emulator" kinda not the case).

Edit:After I RTFA, looks like the drive theory is the correct one.

Play! Load ROM into the emulator, configure the controllers, and you’ll be playing in no time.